Asthma is a chronic inflammatory lung disease characterized by airway hyper-responsiveness and reversible airway obstruction. Over the last decade, the prevalence of asthma is on the rise and it disproportionately affects more women than men. As much as 40% of women with asthma are known to have worsening of asthma symptoms and lung function prior to menstruation. This syndrome is being increasingly recognized as premenstrual asthma (PMA). The pathologic differences in female asthmatics with and without this syndrome are not known. The evidence regarding the role of sex hormones has been contradicting. We propose an observational cohort study to examine the changes in airway inflammation in women with asthma in relation to their menstrual cycle and their association with sex hormone levels. In addition we will include women on oral contraceptives to determine their effect on airway inflammation and asthma symptoms.

We hypothesis that:

Women with premenstrual asthma will show increased indices of airway inflammation in various phases the monthly menstrual cycle.

In women with premenstrual asthma, a change in serum estradiol/progesterone ratio during the late luteal phase is associated with worsening of airway inflammation, air flow limitation and asthma symptoms.

The use of oral contraceptives is associated with suppression of the cyclical changes in airway inflammation due to lack of fluctuations in estradiol and progesterone levels.

Recruited subjects will be asked to record asthma symptom scores, morning Peak Expiratory Flow Rate (m-PEFR) and rescue asthma medication (β2-agonist) used daily during the one month screening period to identify women with and without pre-menstrual asthma. Asthmatic women with regular menstrual cycles will be evaluated in their follicular phase (days 5-8) and luteal phase (days 21-24) and women on oral contraceptive pills (OCP) will be evaluated on days 9-12 of their OCP cycle and during the days 25-28, off of OCP consecutively for a 2-month period.

To analyze the association of between serum estradiol and progesterone levels and the variation in airway inflammation, airflow limitation and asthma symptoms [ Time Frame: 3 months ] [ Designated as safety issue: No ]

To study the effect of oral contraceptives on airway inflammation by measuring serum and exhaled inflammatory indices [ Time Frame: 3 months ] [ Designated as safety issue: No ]

Biospecimen Retention: Samples Without DNA

Serum Eosinophil Cationic Protein (ECP) samples will be obtained. The 5ml blood samples for measuring ECP levels will be collected in silica gel-containing tubes. After centrifuging, the supernatant will be frozen and ECP levels will bemeasured using an ELISA kit

Exacerbation or Respiratory Infection or antibiotic use within the last 30 days

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Please refer to this study by its ClinicalTrials.gov identifier: NCT00584441